Code from the DroidScript-Beta forum posted by Dave Smart

appToBack.js

//Called when application is started.
function OnStart()
{
    //Create a layout with objects vertically centered.
    lay = app.CreateLayout( "linear", "VCenter,FillXY" );    
 
    //Create a button.
    btn = app.CreateButton( "Send To Back", 0.6 );
    btn.SetOnTouch( btn_OnTouch );
    lay.AddChild( btn );
 
    //Add layout to app.    
    app.AddLayout( lay );
 
    //Create media player.
    player = app.CreateMediaPlayer();
 
    //Load a file (can be ogg or mp3).
    player.SetFile( "/Sys/Snd/Poing.ogg" );
    player.SetLooping( true );
}
 
//Called when user touches our button.
function btn_OnTouch()
{
    //Set alarm for 5 seconds time.
    var now = new Date().getTime();
    app.SetAlarm( "Set", 1234, OnAlarm, now + 5000 );
 
    //Set sound playing repeatedly.
    //setInterval( PlaySound, 1000 );
    player.Play();
 
    //Send app to back.
    app.ToBack();    
}
 
//Called when alarm is triggered.
//(Even if your app is closed)
function OnAlarm()
{
    app.ShowPopup( "Hello!" );
}
 
//Play the sound.
function PlaySound()
{
    player.SeekTo( 0 );
    player.Play();
}